Riptide

A riptide is a strong, offshore current that is caused by the tide pulling water through an inlet along a barrier beach.  It is a strong tidal flow of water within estuaries and other enclosed tidal areas. They become the strongest where the flow is constricted.  When there is a falling or ebbing tide, the water is strongly flowing through an inlet toward the ocean, especially once stabilized by jetties.  During these falling and ebbing tides, a riptide can carry a person far offshore.  For example, the ebbing tide at Shinnecock Inlet (picture) in Southampton New York, extends more than 300 m offshore.  Because of this, riptides are typically more powerful than rip currents.  During slack tide, the water is motionless for a short period of time until the flooding or rising tide starts pushing the sea water landward through the inlet.  Riptides also occur in constricted areas in bays and lagoons where there are no waves. These strong, reversing currents can also be termed ebb jets, flood jet, or tidal jets by coastal engineers because they carry large quantities of sand that form sand bars far out in the ocean and in the bay opposite the inlet channel. The term "ebb jet" would be used for a tidal current leaving an enclosed tidal area, and "flood jet" for the equivalent tidal current entering it.

The term "rip tide" or "riptide" is often incorrectly applied to rip currents, which are not tidal flows. A rip current is a strong, narrow jet of water that moves away from the beach and into the ocean.  They can flow quickly and are not predictable and are a result of the shape of the coastline.  A rip tide is caused by the moons gravitational pull and is a predictable rise and fall of the water level.

The US National Oceanographic and Atmospheric Administration comments:

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